WASHINGTON — Forget Sarah Palin. The female maverick of the Republican Party is Sen. Olympia Snowe.

The 62-year-old, moderate Maine lawmaker voted Tuesday for a Democratic health care bill, breaking with her party and giving a major boost to President Barack Obama’s drive to expand coverage to millions of Americans.

“Is this bill all that I would want? Far from it,” Snowe told her colleagues on the Senate Finance Committee. “But when history calls, history calls.”

Snowe had kept virtually all of Washington guessing how she would vote, not even letting Obama, Senate Majority Leader Harry Reid, D-Nev., or Finance Committee Chairman Max Baucus of Montana in on her secret. She did call her Republican leader, Mitch McConnell of Kentucky, Tuesday morning to break the news about her plans.

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When she did speak publicly in committee, she caught Washington’s attention.

“The status quo approach has produced one glaring common denominator, that is that we have a problem that is growing worse, not better,” she said in explaining her support for the bill.

There was much relief in Democratic ranks when she finally said, “Aye,” and the bill was approved 14-9. For months, Obama had pursued her support in phone calls and meetings. Snowe could be the Democrats’ 60th vote required to overcome Republican objections to the bill and give the final version the barest quality of bipartisanship.

“I want to particularly thank Sen. Olympia Snowe for both the political courage and the seriousness of purpose that she’s demonstrated throughout this process,” Obama said during brief remarks in the White House Rose Garden.

Republicans have for weeks grumbled about punishing Snowe should she vote yes at any stage of the lengthy process. One option long discussed: denying her the coveted senior Republican seat on the Senate Commerce Committee.

The best they could do publicly Tuesday was to make clear that she told them her decision before the Democrats found out and to keep communication open with her. Snowe, after all, might well be the sole Republican negotiator at the table when Reid hashes out a final measure for a Senate vote. If so, she represents the GOP’s best chance at winning votes on changes they want.

Not so, said Sen. Pat Roberts, R-Kan.: “Trust me, trust me: A vote for this bill will be a vote for that bill.”

Breaking with her party is a role Snowe has played many times, from her vote for Obama’s $787 billion economic stimulus bill to her defiance of then-President George W. Bush on a bill to provide health care to millions of uninsured children.

Snowe also was one of the “Gang of 14” Democratic and Republican senators who resolved a standoff over judicial nominations.

In Maine, former Gov. Angus King, a political independent, compared Snowe’s decision to the late Republican Sen. Margaret Chase Smith’s “Declaration of Conscience” speech in which she called for the nation — and her own party — to reject McCarthyism.

“This is a vote of conscience and a vote of concern for her constituents and concern for the country. And I think it took plenty of courage,” King said. “I don’t think it’s possible for any of us to fully appreciate the pressure she’s under and has been under to vote with her Republican colleagues.

Said Maine Democratic Gov. John Baldacci: “She wants to move health care forward, she wants to be part of the solution.”

Snowe may face a rough time with her Republican colleagues in the Senate but not necessarily in fiercely independent Maine.

“I don’t think there’s any possible negative political implication,” said Sandy Maisel, director of Goldfarb Center for Public Affairs at Colby College in Waterville, Maine. “She is untouchable electorally in the state of Maine.”

Associated Press writers David Sharp and Glenn Adams in Maine contributed to this report.